Kusal Perera bats with body, heart and soul in innings of a lifetime

That vein.

The vein on Dale Steyn's forehead has come alive. He is mid-pitch, biceps taut, knees bent, fists clenched, face red, practically on fire, screaming.

Mitchell Johnson had three furious seasons. James Anderson nicks entire top orders off. But let's not kid around. If there is a sight that has struck fear into the heart of the planet's batsmen in the last 15 years; if there is a vision that shakes them to their soul, it is this.

Steyn. His vein. Mid-pitch. Screaming.

He has just blasted Oshada Fernando out to claim South Africa's fourth wicket, and two balls later he takes a return catch to send Niroshan Dickwella packing as well, so his team-mates are laughing, broad grins galore, but not Steyn. Steyn is an inferno. He is burning up mere metres from Kusal Perera. It is Kingsmead, but this - be in no doubt - is still Steyn's patch. One of the most fearsome quicks in the history of the game. At home. In a state of almighty fury.

While Steyn scorches up one end, Kagiso Rabada is lightning at the other. His partner is up over 140kph, but Rabada is touching 150, his outswingers whistling past another prod, the slip cordon's hands all up in unison, before the ball has thwacked into the wicketkeeper's gloves. But it is the Rabada bouncer that rears up into your ribs, and the Rabada bouncer that follows Perera like a mugger down an alley. It smacks him on the bottom hand, 65th over. The batsman collapses, a howl on his lips. His finger is already ballooning before the glove comes off.

It has been only 13 days since Perera suffered a mild concussion in Canberra. (The ear guard of his helmet had disintegrated from the blow.) Only 14 overs since Duanne Olivier thudded a 142kph ball into his ribcage. Twenty minutes later, Olivier would crack him on the helmet, too.

While Perera is getting punched, cutting, and counter-punching, at the other end, his team-mates are missing, nicking, and leaving the field. Dhananjaya de Silva, with whom Perera mounted a 96-run defiance, misses a sweep off Keshav Maharaj and is trapped in front. Suranga Lakmal, the only man in the tail who can reliably hang around, edges his first ball to slip.

Four wickets for 20 runs later, Perera still believes, but is he the only one? Would it be a surprise if he was? This is a team that has not won a match since October. No, not just in Tests. One-dayers, T20s, hopscotch, connect four, tic-tac-toe, Sri Lanka players have probably found ways to lose them all.

But then finally, one wicket to go, 78 runs still to get, Perera encounters another believer. "Baya venna epa Kusal aiya," Vishwa Fernando tells him. Don't you worry. "Mama angen hari gahannang." I'll hit the ball with my body, if nothing else.

So two Sri Lanka batsmen - one playing his fourth Test, the other playing his second since being recalled - put their chests, arms, skulls, throats, hands, ribs and balls in danger, against the quickest attack going, for the sake of whatever it is they are fighting for. For their nation, sure, but also for a team that has just dumped its long-term captain, for a head coach convinced his bosses are trying to fire him, and for a system that has let both of them down in unfathomable ways over the whole of their professional careers.

So beautifully is Perera playing, that for South Africa, his wicket is almost irrelevant. This is the best bowling unit in home conditions on the planet - an attack that devoured Pakistan over the last two months, sent Australia squealing into epoch-defining disarray last season, defeated India, monstered Bangladesh, and clobbered New Zealand the season before - flat out refusing to even attempt taking Perera's wicket on a fourth-innings pitch, their fielders all posted on the boundary when he is on strike.

For Vishwa they bring the field in. But Vishwa, through fortune and great personal bravery, somehow misses the outswingers, ducks the bouncers, and clings to his wicket. Perera has already once dived to make his ground, dirtying the front of his whites. Vishwa gets himself in a running tangle as well, and has to make his own full-body, whites-muddying dive. He throws himself at the crease from so far out, he is horizontal, sliding, for what feels like half the length of the pitch.

The runs required decreases. Forty-two now. Hearts thumping. Thirty-four now. Pulses racing.

Then, this is where they come. The shots this match will forever be defined by. The jewels that stud this crown of an innings. A desperate Steyn, looking for swing with the second new ball, still running hot, pitching on off stump, every sinew in his body straining for movement. Perera, clear-headed, forearms rippling, thumping this all-time bowler over midwicket, high over the boundary, way up into the eastern bank.

In years to come, we might still struggle to believe that this embattled and unfancied batsman, in this profoundly embattled and unfancied team, played an innings of such dazzling quality. Could it be the greatest ever?

Overlooked might be the coincidences: that he finished on 153 not out, same as Lara, in 1999. Or that he sealed victory with that left-hander's glide to the third man boundary, same as Ranatunga in 1996.

But unforgettable are the odds he fought, the blows he took, the joy on his face and from his team when it was won.